I believe you can edit your Cod Ghosts data on a website that will be created in the future. Like Call of Duty Elite does now with their website.
I can't recall if they have clearly stated that it will all be available on the PC as well, but I highly doubt they will only do a lot of these things on the App and not via a browser. We'll find out for sure on November 5th. The app is just a great companion to have if you don't have your PC in front of you or if you want to look at something on the go. One way or another, the app is not a requirement and thus most of the stuff is going to have to be available on the website.
Q: I do not want to use the Call of Duty® app, but I’m worried that players who do will have an unfair advantage in Call of Duty®: Ghosts multiplayer with the in-game Call of Duty® Clan Wars rewards.
A: No, the Call of Duty® app will not provide any unfair gameplay advantage in Call of Duty®: Ghosts multiplayer.